FLUOROCARBON EMULSION STABILIZING SURFACTANTS

Surfactants (e.g., fluorosurfactants) for stabilizing aqueous or hydrocarbon droplets in a fluorophilic continuous phase are presented. In some embodiments, fluorosurfactants include a fluorophilic tail soluble in a fluorophilic (e.g., fluorocarbon) continuous phase, and a headgroup soluble in either an aqueous phase or a lipophilic (e.g., hydrocarbon) phase. The combination of a fluorophilic tail and a headgroup may be chosen so as to create a surfactant with a suitable geometry for forming stabilized reverse emulsion droplets having a disperse aqueous or lipophilic phase in a continuous, fluorophilic phase. In some embodiments, the headgroup is preferably non-ionic and can prevent or limit the adsorption of molecules at the interface between the surfactant and the discontinuous phase. This configuration can allow the droplet to serve, for example, as a reaction site for certain chemical and/or biological reactions. In another embodiment, aqueous droplets are stabilized in a fluorocarbon phase at least in part by the electrostatic attraction of two oppositely charged or polar components, one of which is at least partially soluble in the dispersed phase, the other at least partially soluble in the continuous phase. One component may provide colloidal stability of the emulsion, and the other may prevent the adsorption of biomolecules at the interface between a component and the discontinuous phase. Advantageously, surfactants and surfactant combinations of the invention may provide sufficient stabilization against coalescence of droplets, without interfering with processes that can be carried out inside the droplets.